126 University of Kansas Geological Survey. 



confined to the outer side at the extremity of the alar ridge, the 

 surface at its inner side being smoothly convex. The superior 

 surface has the internal process much elongated and narrow, 

 the cavity between it and the alar process deep. 



There are two, perhaps more, distinct types of quadrates in 

 the genus Clidastes, corresponding to the emarginate and non- 

 emarginate coracoid. To the first type belongs C. velox, and 

 C. pumilus, if it be distinct ; while in the second are included 

 C. tortor, C. propython, C. dispar, C. westii, and probably all the 

 others now known. All of these last-mentioned species have 

 quadrates so nearly alike that they do not offer trustworthy 

 specific differences. Differences there are among them, but it 

 is yet to be determined whether any of them are of more than 

 individual importance. The accidental distortions to which the 

 Kansas specimens are liable render it hard to determine which 

 are adventitious and which are structural. The quadrate of 

 G. tortor differs from that of C. velox as follows : The internal 

 border between the superior and inferior angles is deeply con- 

 cave, instead of being nearly straight. The border is smooth 

 and rounded in the concavity, and is more or less sinuous. In 

 C. velox, it is nearly straight, and has a distinct rugosity just 

 in front of the meatal pit, and a distinct ridge below it, both of 

 which are wanting in C. tortor. The articular surface of the 

 suprastapedial process is more narrowed on the upper part, the 

 lower end more dilated. Below the end of the process, near the 

 inner side, there is a more or less strong tubercular rugosity, 

 wanting in C. velox, where the rugosity is toward the posterior 

 side, and is represented by a strong rugose ridge in C. tortor, 

 extending from the tubercular rugosity obliquely to the outer 

 inferior angle. The posterior surface is nearly plane from side 

 to side, and convex from above downward to near the lower 

 part. In C. velox there is a deep and broad channel, and the 

 surface is strongly concave from side to side as well as longi- 

 tudinally. The ala is somewhat less dilated and more elongated 

 vertically. The upper articular surface is much more deeply 

 concave between the anterior and alar processes in C. velox, 

 while the inner border at the base of the suprastapedial process 



